In the past, inflatable devices have been utilized to dissect tissue layers to create an anatomic working space to facilitate the performance of laparoscopic or other minimally invasive surgical procedures. For example, in commonly assigned U.S. Pat. No. 5,514,153 to Peter M. Bonutti, the disclosure of which is hereby incorporated by reference in its entirety, various inflatable devices are disclosed which can be utilized to dissect tissue to create an anatomic working space. A surgical balloon dissector and its methods of use are also disclosed in commonly assigned U.S. Pat. No. 5,496,345, to Kieturakis et al., the disclosure of which is also hereby incorporated by reference in its entirety. It has been found that a tissue pocket formed by balloon dissection is generally more regular and precise than the pocket typically obtained with manual dissection. In contrast to traditional blunt dissection techniques, the dissecting balloon creates a tissue pocket while respecting natural tissue planes or boundaries in the anatomy.
A second class of inflatable devices known as tissue expanders are fluid operated devices which, when inflated, stretch and place pressure on overlying tissues to create tissue growth in a localized area of the body. Tissue expanders have generally been used in plastic or reconstructive surgery as temporary implants to gradually expand a previously dissected pocket over time as the overlying skin and tissue gradually alters (through new cell formation) and expands in response to the force applied by the inflatable tissue expander. Often, the "created" tissue is stretched over an adjacent area where a tissue defect has been removed or where additional tissue is required. Tissue expanders traditionally incorporate inflation ports which are connected by an inflation tube to the expander and are implanted somewhat remote from the expansion site. The inflation ports are small reservoirs which incorporate a self-sealing membrane through which fluid may be introduced by hypodermic needle. The port is placed under the skin such that there is easy needle access to the membrane.
In the conventional use of tissue expanders, it has been customary to make an incision immediately adjacent to or over the region into which the expander is to be subsequently placed, and then to utilize a blunt instrument or the finger to dissect exposed tissue layers to create a pocket. Generally, it is desirable to dissect the pocket adequately such that the dissected footprint easily accommodates the expander without curling the edges of the expander at the dissection margins. Once the expander is placed into the dissected space, the incision through which the dissection and expander placement was accomplished is closed and allowed to heal before the expansion process begins. This step is necessary because the tissue strength at the incision must be reestablished in order to withstand the stresses caused by long term tissue expansion. Otherwise, there is chance that the expander will extrude out of the incision preferentially to expanding the tissue over the dissected footprint, as desired. This healing step may require considerable time (on the order of weeks) before tissue expansion can begin.
Recently and commensurate with the trend toward minimally invasive surgery, practitioners have begun inserting tissue expanders into previously dissected pockets in the body through incisions remote from the expansion site such that the lengthy incision healing step can be eliminated. This advantageously allows expansion to be commenced immediately after placement of the tissue expander. Use of a remote insertion site also requires dissection to be accomplished through the remote incision and that the expanders are capable of being rolled or otherwise compacted to allow for proper placement at the remote site through the incision.
In the tissue expander art, it is also known that excessive inflation pressures in the tissue expander can cause tissue necrosis. Hence, the inflation pressure of the tissue expander must be moderated to avoid necrosis. Because the pressure must be held beneath the necrosis level, tissue expanders are left in place over a prolonged period of time to allow the subcutaneous tissues to gradually alter and expand. This requires monitoring and periodical adjustment of the fluid volume in the expander as the tissue gradually stretches over time.
In certain surgical procedures, especially in plastic surgery procedures, it is necessary to dissect a tissue pocket for the later implantation of a prosthetic device. For example, breast augmentation and reconstruction procedures involve dissecting a space or pocket in the breast and, if necessary, following the dissection step with long term tissue expansion to enlarge the pocket to receive the desired implant. Previously, two or more different devices have been required to perform the dissection and expansion steps.
Johnson et al., U.S. Pat. No. 5,258,026, discloses a surgical procedure for breast augmentation. In Johnson, an incision is made in the umbilicus and an elongate hollow tube carrying an inflatable prosthesis is tunneled above the chest wall to a position behind the breast. The prosthesis itself is then utilized as a tissue dissector by overinflating the prosthesis to 150% of its anticipated ultimate fill volume to create the breast pocket. The prosthesis is then reduced in volume to its intended final volume and left in place. The umbilical incision is then closed and the surgery completed. While Johnson discloses the use of an inflatable member to create a tissue pocket in the breast for the purpose of augmentation, Johnson uses the implant itself to dissect and does not provide a device or method for further expanding the tissue pocket through long term expansion should the size of the initially dissected space be insufficient.
Accordingly, there is a need for an improved device and associated methods of use which incorporate the features of a tissue dissector and long term tissue expander in a single device to overcome the aforementioned disadvantages in the prior art.